1. Field of the Invention
The present invention relates to a photoresist pattern forming method and a microlens array forming method.
2. Description of the Related Art
With an increase in packing density of elements in semiconductor integrated circuits, pattern miniaturization is required. Japanese Patent Laid-Open No. 6-348032 discloses a method of forming a phase shift pattern by forming a photoresist film with unevenness. Hence, in an exposure process, light with an opposite phase is generated in convex portions to cancel exposure light with a normal phase in concave portions so as to set zero light intensity, thereby forming a fine resist pattern that exceeds the resolution limit of the conventional lithography techniques.
In the lithography techniques, the resolution has a limit due, for example, to the wavelength of exposure light. In the method described in Japanese Patent Laid-Open No. 6-348032, to cancel light with an opposite phase and light with a normal phase, the unevenness and depth of a phase shift pattern must be adjusted with very high accuracy, requiring a complex technique.